Diagnostic and other biological assays often require systems for metering dispensing and mixing reagents with sample fluids. The sample fluids may include, for example, patient samples, blood samples, or minute quantities of deoxygenated rybo nucleic acid (hereinafter "DNA") sequences in a buffer fluid. Both manual and automated systems have been available for aliquoting the fluid samples, and assaying the samples with one or more reagents. Manual systems have historically included the glass capillary pipette, the micro pipette, precision syringes and weighing equipment. A variety of biological assays have been and continue to be conducted with manual equipment of the type described.
Relatively sophisticated microbiological assays including micro-enzyme linked immunosorbent sandwich assays (hereinafter "ELISA") can be satisfactorily, if tediously performed manually. The demands of modern antibody/antigen matching, histocompatibility typing, paternity testing, etc. on a vast scale has precipitated the development of various automated assay equipment to more quickly process large numbers of patient samples with various reagents. It is apparent that in order to perform a multiplicity of assays with a single patient sample, the amount of sample must be relatively large, or a small sample must be aliquoted into smaller divisions.
Recent advances in microbiology have provided the biotechnologist with increasingly sophisticated tools for examining genetic material. Restriction enzyme digestion and polymerase chain reaction (hereafter "RED and PCR respectively") have provided geneticists with multiple DNA segments from a single sample for subsequent assaying. All of these advances have increased the need for sample handling and processing techniques which are beyond the ability of the heretofore manual pipetting and other standard laboratory techniques. As a result, the industry has proceeded with the development of highly automated equipment which can rapidly and repeatably handle relatively small quantities of patient samples.
The undertaking of the Human Genome Project exceeds the limits of current fluid sample handling and processing technology. The Human Genome Project is an attempt to map the entire human genetic code, nucleotide by nucleotide. The PCR and RED techniques presently available will therefore produce an extremely large numbers of nucleotide segments which must be assayed in a variety of different ways. In addition, current methods for producing the nucleotide segments are extremely expensive requiring the very wise use of the resultant sample. It is currently calculated that without further advancement in the state of the art, the cost of producing sufficient samples for laboratories around the world will be prohibitive without the development of techniques for handling much smaller samples and reagent volumes.
Therefore, a need exists for a high-precision, small volume fluid processing system which can aliquot and dispense fluid samples in extremely small volumes, react the samples with small quantities of reagents, and perform all of the other steps which may be necessary in a conventional assay. The system should also preferably be relatively highly automated so that the incidence of human error is reduced.